RELATION OF RHEOLOGICAL PROPERTIES OF TESTA OF PISUM SATIVUM L. TO HISTOLOGICAL CHANGES*

The study was undertaken to determine histological distortions occurring in the pea testa (skin) as a result of various force applications. Multi-directional compression caused bending of macrosclereids and flattening of osteosclereids. Unidirectional pressure caused similar deformations plus eventual separation between cells; shearing caused bending, buckling and wedging of macrosclereids; bruising resulted in cracks between macrosclereids and buckling. The existence of a pentosan-cellulose complex in the basal and apical ends of the macrosclereids and in the end wall regions of the osteosclereids, as established by R. M. Reeve of the U.S.D. A., and the triangular arrangement of the osteosclereids might explain the ability of the macrosclereids to bend and buckle and of the osteosclereids to spread in the end wall regions. This in turn contributes to the resiliency and toughness of the testa in the face of varied physical forces.     

INACTIVATION OF LISTERIA MONOCYTOGENES, SALMONELLA ENTERITIDIS AND ESCHERICHIA COLI O157:H7 AND SHELF LIFE EXTENSION OF FRESH-CUT PEARS USING MALIC ACID AND QUALITY STABILIZING COMPOUNDS

ABSTRACT

Inactivation of Listeria monocytogenes, Salmonella enteritidis and Escherichia coli O157:H7 and shelf life extension of fresh‐cut pears using malic acid (MA) and quality stabilizing compounds (N‐acetyl‐L‐cysteine, glutathione and calcium lactate; CGLW) were investigated. Trays of treated fresh‐cut pears were wrap sealed with a thick polypropylene film (64 µm) semipermeable to water vapor, O₂ and CO₂, and stored at 5C for 30 days. Changes in headspace gas, firmness and color of the fresh‐cut pears were also determined. Large reductions of L. monocytogenes (6.57 log₁₀ cfu/g), S. enteritidis (6.60 log₁₀ cfu/g) and E. coli O157:H7 (2.62 log₁₀ cfu/g) just after processing were achieved in those fresh‐cut pears dipped in CGLW + MA. Microbiological shelf life of pear pieces dipped in CGLW + MA was extended by more than 21 days in comparison with those cut pears immersed in water used as control sample. Lower consumption of O₂ and production of CO₂, ethylene and ethanol of fresh‐cut pears dipped in CGLW + MA were also observed. In addition, the color and firmness of pear pieces in CGLW + MA were maintained by more than 21 days in comparison with control samples. In conclusion, the combination of MA with quality stabilizing compounds can be a good alternative for assuring the safety and quality of fresh‐cut pears.

PRACTICAL APPLICATIONS

The use of natural substances generally recognized as safe (GRAS) such as malic acid and N‐acetyl‐L‐cysteine, glutathione and calcium lactate as antimicrobials and quality stabilizing compounds, respectively, can result suitable to fresh‐cut products industry, since they can assure the safety and quality of those products, while improving their sensory attributes and maintaining the fresh‐like and healthy properties of these products greatly demanded by the consumers.     

THE EFFECT OF DIETARY ENERGY-TO-PROTEIN RATIO VARIATION ON THE TASTE QUALITY OF BROILER CHICKEN MEAT 1

Broiler chickens were fed diets varying in their energy-to-protein (E:P) ratio, and then slaughtered at different ages. From one to five weeks of age, the chickens were fed a starter diet, which ranged from 120 to 170 Kcal per % protein, and thereafter the finisher diets ranged from 140 to 190 Kcal per % protein, respectively. The highest relative taste preference of the meat from males was found when the starter dietary E:P ratio was approximately 136, and decreased sharply when it was 150 or more. This preference was independent of the age at slaughter. The highest relative taste preference of the meat from females was found when the age at slaughter was approximately 7.3 weeks. The dietary E:P ratio was of lesser significance, but with some preference toward the higher levels of the experimental range.